This invention relates to the maintenance and testing of communication lines, and in particular, conventional telephone lines. As explained at length in the above referenced applications, communication lines require periodic maintenance, testing and repair. Under such circumstances, it is desirable to provide a program of preventive maintenance in which each telephone line is tested systematically to determine if it is operating properly. Such testing advantageously is performed when individual phone lines are not likely to be used, such as late at night. Because the number of faulty lines that are likely to be detected is relatively small, it is also advantageous to be able to test a large number of lines in one testing period and to generate a report relating to all the lines tested.
In testing telephone lines, however, a considerable amount of time is consumed in tasks that do not relate to the actual testing of operating lines. Thus, dialing time takes up a significant percentage of the total time allocated to the testing of individual lines. In addition, numerous lines at any telephone exchange will not be in use at any given time and therefore will not be in need of any testing.
The time required to dial a group of telephone lines may be reduced by use of equipment available in the TTA unit described in the above referenced "Method and Apparatus for Maintaining Communications Systems". Such equipment takes advantage of the central office switching equipment so as to be able to access the next telephone line in numerical order from a line presently accessed. As a result, when a test is completed on one telephone line, the very next telephone line can be accessed simply by transmitting a control signal to the central office switching equipment. This makes it possible to successively step through the telephone lines in an exchange without losing significant time because of dialing delays. Such apparatus, however, has the disadvantage that it steps through every line in the exchange regardless of whether it is operating or otherwise available for testing. As a result, significant time is lost in accessing non-operational lines and lines that are not otherwise available.